Localisation of vocal fold mass with variation of acoustic parameters

Voice pathology detection has been studied intensively in the signal processing research community using various digital signal processing methods. It is now possible to detect & compare different pathologies of the vocal cords in individuals by comparing the acoustical analysis data of patients. The present study was undertaken aiming to find & analyse acoustical features of voice with intracordal vocal fold lesion & lesions located on vibratory margins of vocal fold. And to set out the management/ rehabilitation protocol in both the case scenarios. Out of 300 patients with dysphonia, total of 60 patients(30 with intracordal pathology and 30 with vibratory margins of vocal fold pathology) were selected for the study based upon the set inclusion & exclusion criterias. Acoustical voice analysis was done based upon parameters like fundamental frequency, jitter (frequency perturbation), shimmer (amplitude perturbation), HNR ratio & MPD & physiological dynamics with the help of PRAAT- Voice analysis software & Stroboscope at ENT Department at CNMC&H & Equilibrium Audio-Vestibular & Voice Clinic, Hoogly. The study demonstrated acoustic parameters varying with location of pathology as well as dynamics of vibration. Acoustic parameters are seen to be affected more in case of pathology on vibratory margin rather than intracordal pathology. Maximum phonation time (MPT) was affected more in case of vibratory margin pathology. Shimmer was also found to be high in case of vibratory margin lesions. Jitter was the only parameter which is more affected in intracordal lesion. HNR was higher in vibratory margin pathology, while, fundamental frequency was reduced in case of intracordal pathlogies.
The quality of voice was observed good with smooth margin, while intracordal pathology had more hoarseness but less breathiness and vice versa with vibratory margin pathology. The hoarseness of intracordal pathology persisted more than pathology on vibratory margin. The rehabilitation and treatment protocol differs drastically in both the conditions.